Cystic fibrosis primarily affects which organ system?

Cystic fibrosis is primarily a genetic disorder that affects the respiratory system due to the accumulation of thick and sticky mucus in the airways. This abnormal mucus can obstruct airflow, leading to frequent lung infections, inflammation, and decreased lung function. The primary gene mutation involved in cystic fibrosis affects a protein called cystic fibrosis transmembrane conductance regulator (CFTR), which plays a crucial role in the regulation of salt and water transport across epithelial cells, prominently in the lungs.

While other organ systems, such as the digestive and reproductive systems, can also be affected by cystic fibrosis, the respiratory system is the most significantly impacted and is often where symptoms manifest first. This is why the correct answer focuses on the respiratory system as the primary organ system affected by the disease.